【正文】 ess a request to update customer information。 ? Faulttolerance: an application can have FB (faulttolerant munication backbone), FC (faulttolerant control services), or FN (no faulttolerance)。 and enquire about the customer’s order history. – The customer service owns all the data related to the customers it is managing and is capable of making other service inquiries on behalf of the calling party in order to provide a unified customer service view. – This means a service is a manager object that creates and manages its set ponents. Serviceoriented architecture benefits ? With a serviceoriented architecture, we can realize several benefits to help anizations succeed in the dynamic business landscape of today: ? Leverage existing assets. ? Easier to integrate and manage plexity. ? More responsive and faster timetomarket. ? Reduce cost and increase reuse. ? Be ready for what lies ahead. ? Serviceoriented architecture is by no means a silver bullet, and migration to SOA is not an easy task. Rather than migrating the whole enterprise to a serviceoriented architecture overnight, the remended approach is to migrate an appropriate subset of business functions as the business need arises or is anticipated. ServiceOriented Architecture Architecture Classification for SOABased Applications ? . Tsai, Chun Fan, Yinong Chen ? Arizona State University， Tempe, AZ 85287 ? {wtsai, fanchun, ? Raymond Paul ? Department of Defense, Washington, DC ? ? JenYao Chung ? IBM T. J. Watson, Research Center ? ServiceOriented Architecture ? The architecture of SOAbased applications is different from traditional software architecture where the architecture is mainly static. ? The architecture of an SOAbased application is dynamic, ., the application may be posed at runtime using existing services. ? Thus SOA has provided a new direction for software architecture study, where the architecture is determined at runtime and architecture can be dynamically changed at runtime to meet the new software requirements. ? Thus a target application is built through service discovery and posing instead of traditional process of designing and coding software. ServiceOriented Architecture ? SOA software has the following characteristics that are different from traditional software: ? Standardbased Interoperability ? SOA emphasizes on standbased interface, protocols, munication, coordination, workflow, discovery, collaboration, and publishing via standard protocols such as XML, SOAP, WSDL, UDDI, HTTP, CPP, ebXML, ebSOA, BPEL, FERA, and OWLS. ? These standards allow services developed on different platforms can interoperate with each other with the knowledge of service specifications only. ? Dynamic Composition via Discovery ? SOA provides a new way of application development by using services just discovered. Furthermore, the position and discovery can be carried out at runtime. ServiceOriented Architecture ? Dynamic Governance and Orchestration ? Execution of services needs to be controlled and several mechanisms are available. One is service governance by policy. More specifically, policies can be specified, checked, and enforced during development time and at runtime. ? The other is orchestration where process execution will be coordinated by a central controller and it is responsible for scheduling the execution of services that may be distributed across a connectivity work such as ESB (Enterprise Service Bus). ServiceOriented Architecture ? Architecture of SOA applications, including IBM SOA Foundation architecture, Microsoft’s Whitehorse, SAP’s NetWeaver, OASIS’s FERA and various enterprise SOA applications such as Enterprise SOA and ServiceOriented Enterprise. Application Architecture Issues ? Due to dynamic nature of SOA, the architecture of SOAbased applications has the following characteristics that are distinct from traditional software architectures: ? Dynamic architecture and dynamic rearchitecture ? Lifecycle management embedded in the operation infrastructure architecture ? In traditional software design, the architecture can not be changed after its deployment. In SOA, the basic building block is not a ponent but a service. ? Services are usually connected to a buslike munication backbone such as an ESB (Enterprise Service Bus). Communications among the services are controlled by a control center, which is also attached to the munication backbone. Application Architecture Issues ? This new approach allows new services to be added into the system without stopping the application. ? Furthermore, a new application can be posed from the existing services by just changing the workflow specification without changing the basic SOA framework. Application Architecture Issues ? IBM SOA Foundation architecture consists of stages: modeling, assembling, deployment, and management. ? Furthermore, runtime governance activities are performed to provide guidance and oversight for the target SOA application. ? The activities in the four stages are performed iteratively. ? Modeling: Gather requirements and establish the application model to represent the system using a set of services. ? Assembling: The designer can either create required services from scratch or find an existing service from a service broker to develop the application according to the model constructed. ? Deployment: The runtime environment is configured to meet the application’s requirements, and the application is deployed into that environment for execution. ? Management: After the application is deployed, the services used in the application are provisioned and monitored for information needed to prevent, isolate, diagnose, and fix any problem that might oc